The League One team blamed an administrative error on the mistake that occurred during their first-round replay against Horsham FC on 3 November.

Barnsley had won the game 3-0.

The FA's ruling means that seventh-tier Horsham will replace Barnsley and face Sutton United in round two.

In a statement on Wednesday, the team said they have accepted the FA's decision and thanked Horsham and the club's chairman for their "understanding and cooperation".

The player in question was not named.

"We would like to apologise to our fans, players and staff for this regrettable error," the club said.

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"This mistake - although unintentional - falls way below the high standards we set at this club and is simply not what you deserve," it said.

The club said it has already conducted a "full internal investigation" and have put safeguards in place to ensure this will never happen again.

Horsham FC chairman, Kevin Borrett, said he understands Barnsley's "immense disappointment" by the decision and wished the club "every success in their pursuit of promotion back to the EFL Championship at the end of the 2023/24 season".